/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.pig.pigpen.editor.editparts;

import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;

import org.apache.pig.pigpen.editor.model.Operator;
import org.apache.pig.pigpen.editor.model.PropertyAwareObject;
import org.eclipse.gef.EditPart;
import org.eclipse.gef.editparts.AbstractGraphicalEditPart;

/*
 * Adapted from code by Phil Zoio at http://www.eclipse.org/articles/Article-GEF-editor/gef-schema-editor.html
 */
public abstract class PropertyAwarePart extends AbstractGraphicalEditPart
        implements PropertyChangeListener {
    public void activate() {
        super.activate();
        PropertyAwareObject propertyAwareObject = (PropertyAwareObject) getModel();
        propertyAwareObject.addPropertyChangeListener(this);
    }

    public void deactivate() {
        super.deactivate();
        PropertyAwareObject propertyAwareObject = (PropertyAwareObject) getModel();
        propertyAwareObject.removePropertyChangeListener(this);
    }

    public void propertyChange(PropertyChangeEvent evt) {
        String property = evt.getPropertyName();

        if (PropertyAwareObject.CHILD.equals(property)) {
            handleChildChange(evt);
            refreshVisuals();
        }
    }

    protected void handleChildChange(PropertyChangeEvent evt) {
        Object newValue = evt.getNewValue();
        Object oldValue = evt.getOldValue();

        if (newValue != null && newValue instanceof Operator) {
            // add new child
            EditPart editPart = createChild(newValue);
            int modelIndex = getModelChildren().indexOf(newValue);
            addChild(editPart, modelIndex);
        } else if (oldValue != null && oldValue instanceof Operator) {
            // remove an existing child
            EditPart partToRemove = null;
            for (Object child : getChildren()) {
                EditPart part = (EditPart) child;
                if (part.getModel() == oldValue) {
                    partToRemove = part;
                    break;
                }
            }
            if (partToRemove != null)
                removeChild(partToRemove);
        }
    }
}